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Polybloks by Polysteel

Insulated Concrete Forms

Insulated Concrete Forms (ICF) are hollow blocks filled with concrete and reinforcement that are used to build dwelling and retaining walls.

Polysteel uniquely use steel ties to produce ICF blocks called Polybloks. These are used to create highly insulated, fire-proof, noise-proof, draught-proof very high thermal mass walls that provide great comfort and are virtually indestructible.

Physical Characteristics

Straight ICF Blocks

EPS & Steel

Polybloks consist of two Expanded Polystyrene Sheets (EPS), 65mm thick, held together by a system of rigid steel galvanised ties.

Higher Insulation

EPS is normally white but Polybloks incorporate graphite which turns the block grey. This increases the insulation value by 20-25%.


1200mm (L) x 600mm (H)
150mm concrete cores: 280mm (W)

Ideal for above ground dwellings, pool halls and garages without reinforcement.


1200mm (L) x 600mm (H)
200mm concrete cores: 330mm (W)

Can be used in basements and retaining walls with the appropriate steel reinforcing bars.

insulated concrete formwork block


Anyone that picks up a Polyblok for the first time will be immediately struck by its rigidity. In fact, it is virtually impossible to bend or twist it out of shape. As a result, the tenons in the mortice and tenon joints around the perimeter of every block stay firmly located in the mortices of the adjacent blocks during concreting.


Polybloks are manufactured in the UK and use metric measurements. Insulated Concrete Forms made in the US and Canada have imperial dimensions such as 96” x 18” and are more difficult to work with on UK sites where all the dimensions are in metric.

Corner ICF Blocks


Polysteel corner blocks allow fast and hassle-free installation, completely avoiding the complexity and time-consuming task of forming corners from straight blocks on site.

Manufacturing Process

The corner blocks are more costly to manufacture because they need their own mould and hence need to be made in a separate production run that also increases costs.

Same Cost

Polysteel provide corner blocks at the same price as straight blocks.


Ferrule Strips

The ferrule strips are buried 10mm below the surface of the EPS. These anchor the ties to the EPS during concreting and provide fixing strips for any installation bracing and internal/external finishes by the use of self tapping screws. The 3m thick steel plate provides a far stronger fixing than a plastic system.


Polybloks use Steel Ties

Polybloks use high tensile wire (3mm diameter) spaced 150mm apart. Many ICF systems use plastic ties spaced 200mm apart – the wider spacing allows the ESP leaves to flex more during concreting so that very high levels of care are required before and during concreting.

Steel Ties Facilitate Concreting

The welded steel wire grids provide all the rigidity required and the 3mm wires provide minimal resistance to the flow of concrete resulting in better compaction and very high quality concrete. The steel wire grid also minimises shrinkage cracking in the concrete.

PREMIUM quality

Polybloks incorporating Galvanised Steel Ties and Ferrule Strips are a Premium Quality product and this is recognised by the many hundreds of users since 2008, widely spread in projects all over the UK.

Polysteel Clips


Polybloks are supplied with steel clips. Each Polyblok is rigidly held to the adjacent unit by anchoring the end tie in each block to the end tie in the next block.

No “Bursts”

The rigidity provided by the steel ties and the clips ensure that Polybloks very rarely suffer from the dreaded “bursts” when the Insulated Concrete Forms come apart and wet concrete floods the site.

Easy to Install

The clips are installed by reaching down inside the joint between adjacent blocks and pushing one clip over the bottom ties and one over the top ties at the ends of the adjacent blocks.


Thermal Mass

Steel ties are extremely good heat conductors and ensure that the 0.36 tons of concrete in every m2 of a 150mm Polyblok concrete wall system is maintained at the same temperature. Polypropylene ties do not provide this advantage.


Temperature Variation

When the external temperature drops or rises it can take 10-12 hours for the concrete walls to reach the same temperature without any energy input.

Summer / Winter

Polyblok walls are based on footings buried deep into the earth, adding to the warming and cooling effects as the concrete is heated from below in winter and cooled from below in summer.

ICF Homes

Houses built in Insulated Concrete Forms such as Polybloks remain much warmer in winter and much cooler in summer.

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